Today, the acquisition of quantities to be measured is an important task, since such measured quantities (e.g. temperature, movement or pressure) are used in a huge variety of applications for optimizing or controlling processes, for example. These measurements have to be taken often in difficultly-accessible areas, so that a self-sufficient power supply and a wireless transmission of measurement data is desired.
However, if energy is extracted from a variable speed rotating machine to power a wireless measurement system, there comes a point when the machine is rotating too slow so that not enough energy can be extracted to do a measurement, for example. This can cause the system to crash or power down. When the machine speeds up to provide enough energy to power the measurement system, the unit must spend time rebooting and connecting to the network. Similar problems occur at battery-powered devices.
Therefore, different methods have been used for such systems. For example, the power generator has been oversized to operate at low rotational speed. Alternatively, the system has large energy storage such that the system can continue to operate at lower speeds. Both options add cost and volume to the product.
Hence, there is a desire for a concept for measuring quantities with improved operating reliability and/or improved behavior during low power supply conditions.